Rory McIlroy defeated by amateur Jefferson Knox at the Masters

On Thursday he ground out a 71 on a warm, breezy day. On Friday he was blown off course and shot 77.

On Saturday he got beat by one of the members.

When McIlroy jarred a six-footer in Friday afternoon’s twilight, he made the cut on the number and earned a spot in Saturday’s opening tee time, 10:15 a.m., a buzzkill result for a pro who began the week with hopes of victory. With the weekend field comprised of 51 participants, an odd number, McIlroy might have thought he’d play as a single, with an official scorekeeper in tow. Instead, he elected to play with a marker. That's when 51-year-old Augusta resident Jefferson Knox laced up his spikes, popped out of the pro shop, and played alongside the two-time major winner.

”He played just like he should be playing in the Masters,” said McIlroy afterward, sounding more than a little dumbfounded.

At first glance, you’d think Knox was sent out as a sacrificial lamb. He’s average height and reasonably fit – essentially, he resembles your typical country clubber — but he didn’t carry same athletic physique as his younger playing partner and was outdriven by McIlroy all day. Knox’s caddie sported a white bib with no name on the back and carried a nylon golf bag with no company logos. If you took only a glance before moving along, you’d guess Knox was a tomato can. The soup of the day.

But in reality, he’s a ringer. Knox holds the course record from the member tees, which is – wait for it – a 61 he shot in 2002. Knox’s swing is gorgeous and he putts Augusta’s treacherous greens like a seasoned veteran, which is of course exactly what he is.

“He obviously knows this place so well and gets it round. I don't think I've ever seen anyone putt the greens as well as he does around here,” McIlroy said. “He was really impressive. I was thinking of maybe getting him to read a few of my putts out there.”

That’s right: Rory McIlroy would welcome some putting tips from a member, and yes, this is the kind of thing that could only happen at Augusta.

Knox has been playing the role of weekend fill-in since 2002, and what happened to McIlroy is no accident. Knox has reportedly beaten about half of his playing partners over the years, which makes you wonder if he might be a real-life version of Caddyshack’s Ty Webb. “He’s one of the better golfers at the club, and we know he can go out there and not get in the way,” said a club spokesman, who added that Knox is a member of Augusta’s “Tee and Cup” committee (so he has that going for him, which is nice). On Saturday Knox had a few jobs to do and he did them well: he played fast (18 holes in three hours), he accurately kept his partner’s score (one under), and he kept McIlroy in good spirits (“he was really nice all the way around,” Rory said).

Knox may be mostly unknown to fans outside Augusta’s inner sanctum, but he had his own cheering section, which included friends and family.

“It’s awesome,” said Lee Knox, Jeff’s 23-year-old son, who was whooping it up as his father protected his lead over McIlroy on the back nine. “Dad was pumped when he found out it was Rory. He went to bed last night at 9:30 and told us he wasn’t nervous, but I could tell he was.”

Knox’s score was not displayed on the giant white boards, but I never saw him take a mulligan or pick up a putt without holing out. He only had one bogey through 17 holes and stood on the 18th tee leading McIlroy by three. But Knox dumped his approach into the front bunker and had to hole a three-foot comebacker for bogey to fend off McIlroy, who birdied the hole.

“I thought he was going to be nice and three-putt the last and we would have a halve,” McIlroy said with a laugh.

Unfortunately, the green coats whisked Knox off the premises without a word to the assembled media, which had gathered to meet Saturday’s unlikely Cinderella. His version of the McIlroy takedown will forever be confined to Augusta’s inner circles.

But we know this: last night Jeff Knox was in bed early. Tonight he has a reason to stay up and celebrate.